using Pgno = System.UInt32;

namespace Community.CsharpSqlite
{
	public partial class Sqlite3
	{
		/*
		** 2008 August 05
		**
		** The author disclaims copyright to this source code.  In place of
		** a legal notice, here is a blessing:
		**
		**    May you do good and not evil.
		**    May you find forgiveness for yourself and forgive others.
		**    May you share freely, never taking more than you give.
		**
		*************************************************************************
		** This header file defines the interface that the sqlite page cache
		** subsystem.
		*************************************************************************
		**  Included in SQLite3 port to C#-SQLite;  2008 Noah B Hart
		**  C#-SQLite is an independent reimplementation of the SQLite software library
		**
		**  SQLITE_SOURCE_ID: 2010-08-23 18:52:01 42537b60566f288167f1b5864a5435986838e3a3
		**
		*************************************************************************
		*/

#if !_PCACHE_H_

		//typedef struct PgHdr PgHdr;
		//typedef struct PCache PCache;

		/*
		** Every page in the cache is controlled by an instance of the following
		** structure.
		*/

		public class PgHdr
		{
			public byte[] pData;          /* Content of this page */
			public MemPage pExtra;        /* Extra content */
			public PgHdr pDirty;          /* Transient list of dirty pages */
			public Pgno pgno;             /* The page number for this page */
			public Pager pPager;          /* The pager to which this page belongs */
#if SQLITE_CHECK_PAGES || (SQLITE_DEBUG)
			public int pageHash;          /* Hash of page content */
#endif
			public int flags;             /* PGHDR flags defined below */
			/**********************************************************************
			** Elements above are public.  All that follows is private to pcache.c
			** and should not be accessed by other modules.
			*/
			public int nRef;              /* Number of users of this page */
			public PCache pCache;         /* Cache that owns this page */
			public bool CacheAllocated;   /* True, if allocated from cache */

			public PgHdr pDirtyNext;      /* Next element in list of dirty pages */
			public PgHdr pDirtyPrev;      /* Previous element in list of dirty pages */
			public PgHdr1 pPgHdr1;        /* Cache page header this this page */

			public static implicit operator bool(PgHdr b)
			{
				return (b != null);
			}

			public void Clear()
			{
				sqlite3_free(ref this.pData);
				this.pData = null;
				this.pExtra = null;
				this.pDirty = null;
				this.pgno = 0;
				this.pPager = null;
#if SQLITE_CHECK_PAGES
this.pageHash=0;
#endif
				this.flags = 0;
				this.nRef = 0;
				this.CacheAllocated = false;
				this.pCache = null;
				this.pDirtyNext = null;
				this.pDirtyPrev = null;
				this.pPgHdr1 = null;
			}
		};

		/* Bit values for PgHdr.flags */
		//#define PGHDR_DIRTY             0x002  /* Page has changed */
		//#define PGHDR_NEED_SYNC         0x004  /* Fsync the rollback journal before
		//                                       ** writing this page to the database */
		//#define PGHDR_NEED_READ         0x008  /* Content is unread */
		//#define PGHDR_REUSE_UNLIKELY    0x010  /* A hint that reuse is unlikely */
		//#define PGHDR_DONT_WRITE        0x020  /* Do not write content to disk */

		private const int PGHDR_DIRTY = 0x002; /* Page has changed */
		private const int PGHDR_NEED_SYNC = 0x004;/* Fsync the rollback journal before
** writing this page to the database */
		private const int PGHDR_NEED_READ = 0x008;/* Content is unread */
		private const int PGHDR_REUSE_UNLIKELY = 0x010;/* A hint that reuse is unlikely */
		private const int PGHDR_DONT_WRITE = 0x020;/* Do not write content to disk */

		/* Initialize and shutdown the page cache subsystem */
		//int sqlite3PcacheInitialize(void);
		//void sqlite3PcacheShutdown(void);

		/* Page cache buffer management:
		** These routines implement SQLITE_CONFIG_PAGECACHE.
		*/
		//void sqlite3PCacheBufferSetup(void *, int sz, int n);

		/* Create a new pager cache.
		** Under memory stress, invoke xStress to try to make pages clean.
		** Only clean and unpinned pages can be reclaimed.
		*/
		//void sqlite3PcacheOpen(
		//  int szPage,                    /* Size of every page */
		//  int szExtra,                   /* Extra space associated with each page */
		//  int bPurgeable,                /* True if pages are on backing store */
		//  int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */
		//  void pStress,                 /* Argument to xStress */
		//  PCache pToInit                /* Preallocated space for the PCache */
		//);

		/* Modify the page-size after the cache has been created. */
		//void sqlite3PcacheSetPageSize(PCache *, int);

		/* Return the size in bytes of a PCache object.  Used to preallocate
		** storage space.
		*/
		//int sqlite3PcacheSize(void);

		/* One release per successful fetch.  Page is pinned until released.
		** Reference counted.
		*/
		//int sqlite3PcacheFetch(PCache*, Pgno, int createFlag, PgHdr**);
		//void sqlite3PcacheRelease(PgHdr*);

		//void sqlite3PcacheDrop(PgHdr*);         /* Remove page from cache */
		//void sqlite3PcacheMakeDirty(PgHdr*);    /* Make sure page is marked dirty */
		//void sqlite3PcacheMakeClean(PgHdr*);    /* Mark a single page as clean */
		//void sqlite3PcacheCleanAll(PCache*);    /* Mark all dirty list pages as clean */

		/* Change a page number.  Used by incr-vacuum. */
		//void sqlite3PcacheMove(PgHdr*, Pgno);

		/* Remove all pages with pgno>x.  Reset the cache if x==0 */
		//void sqlite3PcacheTruncate(PCache*, Pgno x);

		/* Get a list of all dirty pages in the cache, sorted by page number */
		//PgHdr *sqlite3PcacheDirtyList(PCache*);

		/* Reset and close the cache object */
		//void sqlite3PcacheClose(PCache*);

		/* Clear flags from pages of the page cache */
		//void sqlite3PcacheClearSyncFlags(PCache *);

		/* Discard the contents of the cache */
		//void sqlite3PcacheClear(PCache*);

		/* Return the total number of outstanding page references */
		//int sqlite3PcacheRefCount(PCache*);

		/* Increment the reference count of an existing page */
		//void sqlite3PcacheRef(PgHdr*);

		//int sqlite3PcachePageRefcount(PgHdr*);

		/* Return the total number of pages stored in the cache */
		//int sqlite3PcachePagecount(PCache*);

#if SQLITE_CHECK_PAGES
/* Iterate through all dirty pages currently stored in the cache. This
** interface is only available if SQLITE_CHECK_PAGES is defined when the
** library is built.
*/

//void sqlite3PcacheIterateDirty(PCache pCache, void (*xIter)(PgHdr *));
#endif

		/* Set and get the suggested cache-size for the specified pager-cache.
**
** If no global maximum is configured, then the system attempts to limit
** the total number of pages cached by purgeable pager-caches to the sum
** of the suggested cache-sizes.
*/
		//void sqlite3PcacheSetCachesize(PCache *, int);
#if SQLITE_TEST
    //int sqlite3PcacheGetCachesize(PCache *);
#endif

#if SQLITE_ENABLE_MEMORY_MANAGEMENT
/* Try to return memory used by the pcache module to the main memory heap */
//int sqlite3PcacheReleaseMemory(int);
#endif

#if SQLITE_TEST
    //void sqlite3PcacheStats(int*,int*,int*,int*);
#endif

		//void sqlite3PCacheSetDefault(void);

#endif //* _PCACHE_H_ */
	}
}